Drilling Knife Tang

[Bloodroot]

I have an Old Hickory knife that I'm reshaping, etc. I want to drill new and smaller holes for pins. Suggestions as to the best way to go about this.

 

[Rifleman1776]

I am not a machinist or metallurgical guy. The answers you may get will be of interest to me also. But, as a layman on this issue, I'm thinking :hmm: the hard steel might be a challenge to drill. I would just go with large pins or knife handle screws.

 

[crockett]

You don't want to take the temper out of the blade so you can wrap the blade in wet rags and heat up the tang to cherry red and let cool. This softens the tang area BUT the problem is you might get a slight warp, bend, or twist. The other option is one of the cobalt type drills for metal- you'll wear out the drill but it should work.
Epoxy glue and "fake" pins that don't go through the tang is yet another option.

 

[ohio ramrod]

Another method is to clamp pieces of copper the the tang just ahead of where you want to heat and drill.The copper acys as a "heat sink" to preserve the temper beyound it. Either method requires that you work fast . :idunno: :idunno:

 

[LRB]

If the Old Hickory's are still 1095 steel, you only need to bring the area to drill up to a very low, barely any red color and air cool a few times. This will spheroidize the carbon/carbides and allow easier working. The blade will still need heat protection though, but warping should not happen.

 

[Bloodroot]

Wick,
What type of drill bit would you suggest? And I would imagine that drilling at a lower speed would be best?

 

[LRB]

I normally use cobalt bits. My Craftsman drill press stays set on the slowest speed. I don't use lube. In my experience, and others may vary, with cobalt bits using a lube just makes a mess and doesn't seem to cut any better. Your most forward hole could be a problem. You will not want the heat to travel forward of where the grips will terminate, or the blade may want to set bend in use. One of those small pencil point torches may be of good use for this.

 

[davec2]

You could also check with a local machine shop that does EDM work (Electrical Discharge Machining). They can go through hardened material with no heat and no softening of the blade material required. Some shops will EDM a hole through for you for very little $...sometimes for nothing. Might not hurt to ask.

 

[paulvallandigham]

Years ago, I bought a couple of knife blades to make patch ( cutting) knives. They were " Laminated Swedish steel" , and an ordinary drill bit would not touch them cold.

However, when I clamped the blades in my bench vise, with just the tang sticking above the top of the jaws, so that the bench vise acted as a "HEAT SINK", to draw heat away from the actual blade, I heated the tang red hot with my propane torch, and that ordinary drill bit cut thru the tangs as if they were made of soft pine, or balsa wood! Long curls of steel came out the flutes of the drill bit.

I let the tangs cool in the air, but you can dunk them in water to cool them faster if you wish.

Heating the tang of your " Old hickory" should be easier than working with those laminated, stainless steel blades I had. And drilling new holes should be a snap. Just don't push that drill with all your might, or you could lose your balance, and fall onto that hot metal. :shocked2: :shocked2: :thumbsup:

 

[Bloodroot]

Thanks for the great suggestions and info. I'll let you all know what I try and how it goes.

 

[Elnathan]

I let the tangs cool in the air, but you can dunk them in water to cool them faster if you wish.

If you try dunking them in water to cool them off, you will quickly learn the difference between annealing steel and quenching it. :wink:

If you want to soften steel, you heat it up and let it cool off sloooowly. Some steels, like O-1, won't anneal unless you bury it in ashes or something overnight - letting it air-cool results in steel that is still too hard to cut easily. Some steels will anneal with air-cooling.

 

[ohio ramrod]

Yea I have cut a few hundred holes in tangs with a "tap burner". When they closed the shop where I had retired from and auctioned off the equipment I tried to buy it but it went to high for me. :idunno: :idunno:

 

[paulvallandigham]

Loki. The blades I used were already formed, finished, polished, hardened, and tempered. Laminated steel has a very thin piece of hard steel in the center of two thicker, and softer( metallugically speaking) pieces of stainless steel.

Unfortunately, those steels run thru the tang, too. ONCE the holes for the pins are drilled for the pins to hold the handle to the tang, there is NO NEED to anneal the tang- even temporarily!

Now, If you want to reshape the tang, You will need to anneal it properly, to make it easy to grind, file or cut with saws, or sanding belts.[BTDT! :surrender: ] Then, of course, you have to now harden the blade again, and then properly temper it, then polish the discoloration off the blade from these processes to make it presentable.

What I was doing was only making, and installing antler handles on the short blades I bought. The process I described here will work on any blade- even one take from a commercially made knife like the " Old Hickory"-- where the owner has removed the rivets, and the original wood slabs.

Here, he wants to drill new holes in the tang for small pins to hold his choice of a new handle( Haft). There is no reason for him to have to Anneal the entire blade just to do this limited work. On such a thin blade( I still own such Ia knife I bought back in 1968, New) If he wants to reduce the width of the blade, he can do so with a grinding wheel "AS IS", ie. without annealing, provided that he keeps the blade and tang cool to the touch by dipping the blade frequently into a container of water.

I hold the blade in my bare hands when grinding so I know immediately when I NEED to dip that blade into the water to cool it down. I can assure you that my flesh burns at a Much lower temperature than it takes to ruin the temper of a knife blade. :shocked2: :hatsoff:

 

[LRB]

Slow cooling works for steels that have less than .8 carbon, but is not so good for those having more, like 1095, or 01. Heating to around 1250° then air cooling will soften those, and they can be quenched when the heat drops under 900° and be soft enough to drill or file.

 

[gmarc]

Use a carbide bit....if you drill promptly, there is little danger of softening the tang, as the surface is quite large.

Even so, a slight loss of hardness in the tang is not problematic unless the softening occurs at a stress point, like the tang/blade junction.

 

[Elnathan]

Slow cooling works for steels that have less than .8 carbon, but is not so good for those having more, like 1095, or 01. Heating to around 1250° then air cooling will soften those, and they can be quenched when the heat drops under 900° and be soft enough to drill or file.

Really? My experience has been completely the opposite - O-1 never has softened completely save when I heated it up to red-hot and buried it in ashes. Just air-cooling it left it so hard that filing was almost impossible. On the other hand, I lost a good metal chisel because after tempering the cutting edge, with the shank still at a black heat, I put it in the slack tub to cool it down. The shank broke first time I used it - it had partially hardened and was too brittle.

Simple carbon steels seem to soften better than O-1 with just air cooling. Such has been my experience, anyhow.

 

[Elnathan]

Paul,
Your last post puzzles me a bit.

If you heat tool steel red hot and then dunk them in water, as you suggested doing in your previous post that I quoted, as a general rule they harden, not soften. Hence my comment.

 

[LRB]

Mine was a blanket statement, assuming the 01 or 1095 was already hardened. If not, no, I would not quench, but would air cool from 1200° to 1250°, but not as a step during a cool down from a higher heat. It would a separate heat going from ambient to 1200° to 1250°, short soak, then air cool. I do this anytime I need to drill a hole in a stick tang after heat treat, but do it with a torch bringing the heat to a very low, barely reddish color a few times. If 01 is brought to a bright red and air cooled, it will harden to a degree that a drill won't cut it well, or often at all, but then give it a low red heat, and cool, it will become soft enough to drill or file. To make it dead soft requires a more complicated process, but the last step is cooling from 1200° to 1250°. In that heat range carbides ball up rather than going into solution, and remain so, and when machined, drilled, or filed, more or less shift out of the way of cutting edges of tooling. Because of the extra carbon, over .8, the carbon forms into hard sheets in a pearlite/cementite mix if a standard slow anneal is used, and is not as soft as a spheroidized anneal.